The alpha-fetoprotein (AFP) test is an item that is commonly included in health screening packages in Singapore. What is the significance of AFP as a tumor marker, how is it used in diagnosing and managing liver cancer, and what is the procedure involved in AFP testing? Learn more about AFP tumor marker in this article.
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What Is Alpha-Fetoprotein (AFP)?
Despite the seemingly negative sounding label of being a tumor marker, Alpha-fetoprotein (AFP) is actually a protein that is needed for fetal development. It is a glycoprotein predominantly produced by the fetal liver and yolk sac during pregnancy. AFP levels in the blood should decrease soon after birth and will remain low in adults that are healthy.
However, when the level of AFP is elevated above the norm, it can be indicative of liver cancer and certain other types of cancer, and also various medical conditions such as liver disease.
AFP Tumor Marker And Liver Cancer
Usage As A Screening Tool
AFP is commonly used as a tumor marker in liver cancer screening, in particular, for hepatocellular carcinoma (HCC). This is the most common type of liver cancer. An elevated AFP level can be an early sign liver cancer which may prompt the doctor to order further medical imaging and biopsies to confirm the cancer.
Usage In Monitoring Of Liver Cancer Treatment
Doctors monitor AFP levels regularly to assess the effectiveness of liver cancer treatment for patients. If the AFP levels drops significantly, it is often indicative of a positive response to treatment. Conversely, if levels rise, it may indicate a recurrence or growth of the tumor.
What To Expect During An AFP Tumor Marker Testing
Prior to the test:
- Fasting or avoidance of certain medications may be require to ensure accurate results.
The test itself:
- Is performed in a clinical setting such as a hospital or a diagnostic lab.
- Involves taking a sample of blood from the patient.
- Usually takes less than five minutes.
After blood drawing:
- Patients can immediately resume normal activities.
- There are no significant associated side effects.
What Levels Of AFP Are Indicative Of Liver Cancer?
The level of AFP in the blood stream is measured in units of nanograms per millilitre (i.e. ng/mL). One nanogram is one-billionth of a gram. A millilitre is 1/1000 litre.
- Normal Levels: Healthy adults are expected to have AFP levels below 10 ng/mL.
- Associated With Other Liver Conditions: Certain liver conditions such as liver regeneration or active hepatitis may cause AFP levels to be moderately elevated.
- Indicative of HCC: An ATP level in excess of 500 ng/mL is strongly indicative of hepatocellular carcinoma. This will be especially so if the patient has an underlying condition such as liver cirrhosis or chronic hepatitis.
Limitations of AFP Tumor Marker Testing
Possibility Of False Positives And False Negatives
A limitation of AFP tumor testing is that it is not a foolproof test for liver cancer. There is a possibility of results that are false positives or false negatives.
- False Positives: This is when AFP level is elevated by there is no cancer. Non-cancerous liver conditions like hepatitis and cirrhosis can cause elevated AFP levels. False positives may cause patients to feel unnecessary anxiety and undergo additional tests.
- False Negatives: This is when the AFP level is not elevated even though there is cancer. This can arise because some liver cancer patients do not exhibit elevated AFP levels, especially in early stages. False negative results can potentially allow the cancer to remain undetected.
Variability In AFP Levels
- Individual Variability: Factors such as age, gender, and ethnicity can influence AFP levels, making it difficult to establish a universal threshold for judging what can be truly considered an “elevated level” for a specific patent.
- Tumor Characteristics: Some types of liver tumours produce little to no AFP, unlike HCC. This limits the effectiveness of AFP tumor marker as a universal test for all forms of liver cancers.
Limited Specificity
- Non-Specific Marker: AFP can also be elevated by other cancers and non-cancerous conditions. It would be necessary to undergo additional tests to determine the actual cause of the elevated AFP level.
AFP Screening And Importance Of Accurate Interpretation Of Results
AFP is an important tumor marker for early detection (and management) of liver cancer. Early diagnosis of cancer can lead to improved treatment outcomes. People with risk factors for liver cancer should give serious consideration to regular AFP testing. Due to the limitation of the test, however, it is important to interpret AFP levels in conjunction with other diagnostic tools to ensure accuracy both in diagnosing and in effective monitoring of liver cancer.
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This article is informative only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment, and should never be relied upon for specific medical advice.